IPAC2017 - List of Authors (Huang, Z.)

Paper	Title	Page
WEPAB108	Angular Trajectory Kicks in a High-Gain Free-Electron Laser	2830
	P. Baxevanis, Z. Huang, G. Stupakov SLAC, Menlo Park, California, USA
	In a free-electron laser (FEL), transverse momentum offsets (or kicks) are introduced either inadvertently (through wakefields or mis-steering of the electron beam) or as part of dedicated schemes that require off-axis radiation propagation. Studying the influence of this effect on the performance of machines such as LCLS-I/II is critical both from a tolerance point of view and for its practical applications. A theoretical analysis of a high-gain FEL driven by such a kicked beam will be presented, with a critical evaluation of previous studies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB108
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WEPAB109	Multipole Field Effects in a Transverse Gradient Undulator	2833
	P. Baxevanis, Z. Huang SLAC, Menlo Park, California, USA
	Using a transverse gradient undulator (TGU) is one of the methods proposed in order to enable the utilization of electron beams with large energy spread (such as those from plasma-based accelerators) in a free-electron laser (FEL). Most of the analytical treatments of this scheme assume a linear variation of the undulator field with one of the transverse coordinates. While this assumption leads to a simplified and more tractable model, including higher-order multipoles allows us to offer a more complete and rigorous description of the system. In this paper, we investigate the magnetic field components of a TGU using both theory and simulation and explore the impact of higher-order multipoles on the FEL performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB109
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WEPAB116	LCLS Injector Laser Shaping and Applications	2844
	S. Li, S.C. Alverson, D.K. Bohler, A.B. Egger, A.R. Fry, S. Gilevich, Z. Huang, A. Miahnahri, D.F. Ratner, J. Robinson, F. Zhou SLAC, Menlo Park, California, USA
	In the Linear Coherent Light Source (LCLS) at SLAC, the injector laser plays an important role as the source of the electron beam for the Free Electron Laser (FEL). The beam emittance and FEL performance are highly related to the transverse shape of the injector laser. When the injector laser has hot spots and non-uniformities that can carry over to the electron beam and degrade electron emittance and FEL performance, it requires long hours of manual adjustment by laser engineers and strenuous machine tuneup. The injector laser shaping project at LCLS aims to have precise control of the driver laser transverse profile in order to produce arbitrary electron beam profiles, which will enable us to study effects of laser shape on beam emittance and FEL performances. We use a digital micromirror device (DMD) to manipulate the drive laser profile. In this paper, we briefly discuss the implementations of laser shaping at LCLS. We demonstrate two applications of laser shaping. We present results of using laser shaping to control the X-ray laser output via an online optimizer. We also show the photocathode quantum efficiency measurements across cathode surface using the DMD.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB116
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WEPAB118	High Power Sub-Femtosecond X-Ray Pulse Study for the LCLS	2848
SUSPSIK017	use link to see paper's listing under its alternate paper code
	J.P. MacArthur Stanford University, Stanford, California, USA J.P. Duris, Z. Huang, A. Marinelli SLAC, Menlo Park, California, USA
	The desire to resolve sub-femtosecond electron dynamics has pushed FEL facilities to shorter pulse lengths. However, current short-pulse schemes provide low pulse energy and a gain-length limited lower bound on the pulse duration. The X-ray Laser-Enhanced Attosecond Pulses (XLEAP) project at SLAC is designed implement an Enhanced Self Amplified Spontaneous Emission (ESASE) scheme, which produces sub-fs current spikes by modulating and compressing the electron beam. We show through a series of Genesis simulations that the current spike is capable of producing sub-fs pulses with a peak power well above 100 GW. Space-charge induced beam chirp can decrease pulse lengths below 400 as, and multi-stage schemes can increase peak x-ray powers to around 1 TW.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB118
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THPAB078	Beam Dynamics Studies of the Transverse Gradient Undulator and Its Application to Suppression of Microbunching Instability	3895
	T. Liu, Y. Ding, Z. Huang, W. Qin SLAC, Menlo Park, California, USA T. Liu University of Chinese Academy of Sciences, Beijing, People's Republic of China T. Liu, D. Wang SINAP, Shanghai, People's Republic of China
	A transverse gradient undulator (TGU) which was initially proposed for high gain free electron lasers (FELs) driven by electron beams with relatively large energy spread, can be extended to the application of beam dynamics, such as phase-merging enhanced harmonic generation FEL and suppression of microbunching instability. In this contribution we present beam dynamics studies of the TGU, analyze the resulting focusing and dispersion, and discuss the effects of an additional corrector on the TGU. As an application to beam dynamics, we show a feasible transport system based on the TGU as a reversible electron beam heater to suppress the microbunching instability of the electron beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB078
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Paper

Title

Page

Angular Trajectory Kicks in a High-Gain Free-Electron Laser

2830

P. Baxevanis, Z. Huang, G. Stupakov
SLAC, Menlo Park, California, USA

In a free-electron laser (FEL), transverse momentum offsets (or kicks) are introduced either inadvertently (through wakefields or mis-steering of the electron beam) or as part of dedicated schemes that require off-axis radiation propagation. Studying the influence of this effect on the performance of machines such as LCLS-I/II is critical both from a tolerance point of view and for its practical applications. A theoretical analysis of a high-gain FEL driven by such a kicked beam will be presented, with a critical evaluation of previous studies.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB108

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB109

Multipole Field Effects in a Transverse Gradient Undulator

2833

P. Baxevanis, Z. Huang
SLAC, Menlo Park, California, USA

Using a transverse gradient undulator (TGU) is one of the methods proposed in order to enable the utilization of electron beams with large energy spread (such as those from plasma-based accelerators) in a free-electron laser (FEL). Most of the analytical treatments of this scheme assume a linear variation of the undulator field with one of the transverse coordinates. While this assumption leads to a simplified and more tractable model, including higher-order multipoles allows us to offer a more complete and rigorous description of the system. In this paper, we investigate the magnetic field components of a TGU using both theory and simulation and explore the impact of higher-order multipoles on the FEL performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB109

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB116

LCLS Injector Laser Shaping and Applications

2844

S. Li, S.C. Alverson, D.K. Bohler, A.B. Egger, A.R. Fry, S. Gilevich, Z. Huang, A. Miahnahri, D.F. Ratner, J. Robinson, F. Zhou
SLAC, Menlo Park, California, USA

In the Linear Coherent Light Source (LCLS) at SLAC, the injector laser plays an important role as the source of the electron beam for the Free Electron Laser (FEL). The beam emittance and FEL performance are highly related to the transverse shape of the injector laser. When the injector laser has hot spots and non-uniformities that can carry over to the electron beam and degrade electron emittance and FEL performance, it requires long hours of manual adjustment by laser engineers and strenuous machine tuneup. The injector laser shaping project at LCLS aims to have precise control of the driver laser transverse profile in order to produce arbitrary electron beam profiles, which will enable us to study effects of laser shape on beam emittance and FEL performances. We use a digital micromirror device (DMD) to manipulate the drive laser profile. In this paper, we briefly discuss the implementations of laser shaping at LCLS. We demonstrate two applications of laser shaping. We present results of using laser shaping to control the X-ray laser output via an online optimizer. We also show the photocathode quantum efficiency measurements across cathode surface using the DMD.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB116

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WEPAB118

High Power Sub-Femtosecond X-Ray Pulse Study for the LCLS

2848

SUSPSIK017

use link to see paper's listing under its alternate paper code

J.P. MacArthur
Stanford University, Stanford, California, USA
J.P. Duris, Z. Huang, A. Marinelli
SLAC, Menlo Park, California, USA

The desire to resolve sub-femtosecond electron dynamics has pushed FEL facilities to shorter pulse lengths. However, current short-pulse schemes provide low pulse energy and a gain-length limited lower bound on the pulse duration. The X-ray Laser-Enhanced Attosecond Pulses (XLEAP) project at SLAC is designed implement an Enhanced Self Amplified Spontaneous Emission (ESASE) scheme, which produces sub-fs current spikes by modulating and compressing the electron beam. We show through a series of Genesis simulations that the current spike is capable of producing sub-fs pulses with a peak power well above 100 GW. Space-charge induced beam chirp can decrease pulse lengths below 400 as, and multi-stage schemes can increase peak x-ray powers to around 1 TW.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB118

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB078

Beam Dynamics Studies of the Transverse Gradient Undulator and Its Application to Suppression of Microbunching Instability

3895

T. Liu, Y. Ding, Z. Huang, W. Qin
SLAC, Menlo Park, California, USA
T. Liu
University of Chinese Academy of Sciences, Beijing, People's Republic of China
T. Liu, D. Wang
SINAP, Shanghai, People's Republic of China

A transverse gradient undulator (TGU) which was initially proposed for high gain free electron lasers (FELs) driven by electron beams with relatively large energy spread, can be extended to the application of beam dynamics, such as phase-merging enhanced harmonic generation FEL and suppression of microbunching instability. In this contribution we present beam dynamics studies of the TGU, analyze the resulting focusing and dispersion, and discuss the effects of an additional corrector on the TGU. As an application to beam dynamics, we show a feasible transport system based on the TGU as a reversible electron beam heater to suppress the microbunching instability of the electron beam.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB078

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)